We propose to continue our electrophysiological studies of single neurons in retina, lateral geniculate nucleus, and striate cortex of normal and visually deprived cats. Two related objectives, both representing a continuation of ongoing studies, are sought. First, we shall continue to study spatial and temporal contrast sensitivity functions from single neurons. We hope to determine the pattern and locus of previously described deficits for these functions among X- and Y-cells, and extend this to W-cells and cortical neurons. Second, we shall continue our effort directed at intracellular recording and HRP injection of individual, physiologically identified neurons. The HRP completely stains the neuron, including fine dendritic and axonal processes, and this permits structure-function relationships to be established at the single neuron level. We plan to use this method first to determine these relationships for normal cells and then to study them after visual deprivation. We expect these approaches to provide insights into both the mechanism involved in visual development as well as the structural relationships to functionally described neuroplastic changes.